Plunger with flow passage and chamber

ABSTRACT

A chamber for use in plungers used in wells that produce liquids and/or gases under, which is connected to an internal flow passage to facilitate more rapid descent of the plunger to the well stop. A closure means is housed within the chamber, and is in the open position when the plunger descends down the tubulars. The closure means is actuated when the plunger and stopper stem reach the well stop. Once the closure means is seated, it is held in the closed position by the build up of pressure below the plunger. The invention also covers a plunger and a method of using the plunger.

RELATED APPLICATIONS

This application is a continuation in part of U.S. application Ser. No. 10/077,457, filed Feb. 15, 2002, that is still pending.

FIELD OF THE INVENTION

The present invention relates to improvements in plungers used in a gas/fluid lift system in wells producing both fluids and gases, such as petroleum and natural gas, under variable pressure to facilitate the lifting of fluids from a subterranean reservoir to the surface through a well conduit or tubulars.

Another further improvement concerns a valve-like assembly used to regulate and restrict the flow of fluids and gases through an internal passage in plunger that allows such plungers to descend to the well bottom more rapidly than plungers without internal passages.

BRIEF DESCRIPTION OF THE DRAWINGS

Details of this invention are described in connection with the accompanying drawings that bear similar reference numerals in which:

FIG. 1 is a schematic representation of an operating well and production of the well by utilizing a gas operated plunger according to an embodiment of the invention;

FIG. 1A shows an embodiment of plunger according to this invention that is descending in the production tubulars and has the closure member in the open position;

FIG. 1B shows an embodiment of plunger according to this invention in the production tubulars, with the closure member in the closed position;

FIG. 1 is a schematic representation of an operating well and production of the well by utilizing a gas operated plunger according to an embodiment of the invention;

FIG. 2 is a longitudinal, external view, of a gas operated plunger;

FIG. 3 is a top inner perspective view of the four segments of the embodiment of FIG. 2;

FIG. 4 is an inner, perspective view of the grooved core and jacket assembly of the segments of FIGS. 2-3, with one of the segments removed;

FIG. 5 is a longitudinal view of two of the four cooperating segments that form the jacket assembly for use with the preferred embodiment of FIG. 18;

FIG. 6 is a view of the upper end of the four segments of FIG. 5;

FIG. 7 is an inner, perspective view of one of the segments of FIGS. 5-6;

FIG. 8 is an outer perspective view of one of the segments of FIGS. 5-6;

FIG. 9 is an inner planar, or flattened, perspective view of one of the segments of FIGS. 5-7;

FIG. 10 is an outer planar, or flattened, perspective view of one of the segments of FIGS. 5-6, 8;

FIG. 11 is a cross-sectional view of the segments of FIGS. 6, 9, taken across lines D-D of FIG. 9;

FIG. 12 is a cross-sectional view of the segments of FIGS. 6, 9, taken across lines A-A of FIG. 9;

FIG. 13 is a cross-sectional view of the segments of FIGS. 8, 10, taken across lines C-C of FIG. 10;

FIG. 14 is a cross-sectional view of the four segments of FIGS. 5, 6, taken across lines B-B of FIG. 10;

FIG. 15 is a cross-sectional view of the segments of FIGS. 8, 10, taken across lines B-B of FIG. 10;

FIG. 16 is a detailed drawing, partially in section, illustrating the biasing means of the preferred embodiment of FIG. 18, and the sectional view of the grooves and segments of FIGS. 9, 12;

FIG. 17 is a detailed drawing, partially in section, illustrating the flow in the area between the segments and grooves in FIG. 16 of the preferred embodiment of FIG. 18;

FIG. 18 is a longitudinal view, in quarter section, of a preferred embodiment of a gas operated plunger;

FIG. 19 is an outer perspective view of the installation of one of the segments underneath a retaining ring;

FIG. 20 is a longitudinal view, in quarter section, of a gas operated plunger that has a chamber and an internal passage and valve closure means in the open position;

FIG. 21 is the top view of the fishing piece of the plunger of FIG. 20;

FIG. 22 is the bottom view of the plunger of FIG. 24;

FIG. 23 is a sectional view of the chamber of the plunger of FIG. 20 with the closure means in the closed position;

FIG. 24 is a sectional view of the chamber of an alternate embodiment of a plunger and a plunger stopper in the open position;

FIG. 25 is a sectional view of the chamber of an alternate embodiment of a plunger and a plunger stopper in the closed position;

FIG. 26 is a longitudinal cross-sectional view of a spiral plunger;

FIG. 27 is a longitudinal cross-sectional view of a spiral plunger;

FIG. 28 is a longitudinal cross-sectional view of a spiral plunger;

FIG. 29 is a longitudinal cross-sectional view of a spiral plunger;

FIG. 30 is a longitudinal cross-sectional view of a spiral plunger;

FIG. 31 is a longitudinal cross-sectional view of a Teflon coated plunger;

FIG. 32 is an external view of plunger with pads;

FIG. 33 is an external view of a brush plunger;

FIG. 34 is an external view of a plunger with washers;

FIG. 35 is a is a longitudinal cross-sectional view of a plunger with a grooved mandrel and pads with fingers;

FIG. 36 is a is a longitudinal cross-sectional view of a plunger with pads;

FIG. 37 is a longitudinal cross-section view of a spiral plunger with an internal fishing piece in the closed position;

FIG. 38 is a longitudinal cross-sectional view of a spiral plunger with an internal fishing piece in the open position; and

FIG. 39 is a top cross-sectional view of the chamber of FIGS. 37-38.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides a plunger for use in tubulars in wells producing both liquids and gases under variable pressure. The plunger assists with the build up of pressure between the subterranean reservoir and the surface by having an inner seal and an external sliding and variable holding seal with adjacent well tubulars. The inner and external seals restrict the upward flow of the liquids and/or gases. This causes an increase in the well pressure below the plunger and facilitates the upward lifting of the plunger and gases and/or liquids from the reservoir to the surface when pressure is reduced above the plunger, such as at the well head.

The improved plunger comprises a body which is slidingly engageable and which gravitates within the tubulars. The plunger body may have an external sealing means such as a plurality of segments which are mounted around a core, also known as a mandrel, and which collectively form a jacket. The segments, collectively the jacket assembly, are slidingly and sealingly engageable with the insides of the well tubulars, based upon the pressure affected between the inner surface, or inside, of the jacket and the core. The jacket has the largest diameter of the plunger when the segments are in an expanded radial position. The segments have a convex outer surface and typically have a concave inner surface. However, the core of the plunger could be square, triangular, or of another geometric shape, in which case the inner surfaces of the segments could be flat, or of any other corresponding geometric shape.

In an embodiment of the plunger, there is also an inner sealing means such as at least one rigid finger which projects radially inward from the underside of each segment toward the core, with the fingers of the adjacent segments collectively cooperating to encircle the core. Preferably, there are a plurality of fingers on the undersides of each segment. The fingers are normally separated from the core especially when the segments, collectively the jacket, are pushed radially outward. When the fingers are separated from the core, the fingers collectively create a tortuous path of flow between the core and the segment undersides and affect a turbulent inner seal. When the segments making up the jacket are pushed to their most radially inward position, the fingers touch the core and cause a complete inner seal.

In a further embodiment, the core has at least one circumferential groove on its surface, and more preferably a plurality of grooves. This also creates a tortuous path of flow between the core and the jacket underside and affects an inner seal. In another embodiment, the plunger has both grooves and fingers, and the fingers are correspondingly located to fit into the grooved portions of the core. This design creates an even more tortuous path of flow for liquids and gases which effects an inner seal and creates an increased surface area between the segments and core. The increased surface area also has the effect of increasing the internal plunger pressure, i.e., the pressure between the core and the jacket assembly and energizes the segments, pushing the segments radially outward toward the well tubulars. This preferred design also prevents detachment and/or loss of the segments if the retainer rings, explained below, fail because the segments will be held in place by the finger-groove interface and by the outer well tubulars. This design provides for increased functionality and seeks to minimize expensive and time consuming fishing operations to retrieve dislocated parts.

In a plunger that has external pads, there is at least one biasing means, which is typically a spring, between the underside of each segment and the core to outwardly bias each segment and to achieve inward and outward radial rebounding of the segments from the inner core. The preferred embodiment also has recessed spaces, or blind holes, in the core or core grooves and/or the fingers that hold the biasing means in place between the core and segments and prevent displacement and loss of the biasing means. The preferred embodiment typically also has retaining means such as retaining rings that limit the outward radial movement of the segments/jacket assembly. In plungers with both fingers and grooves, at least one of the outside edges of the grooves will be angularly reduced to allow installation of segments with projecting fingers into the grooves of the core and allows the end of the segments to be installed underneath the retaining rings.

In yet another embodiment of the invention, the plunger has an internal passage that extends part way through the body, or through the entire axis of the plunger, to facilitate a more rapid descent of the plunger to the bottom of the well or the well stop means. These plungers may further have a chamber in a modified end cap near the bottom end, which houses a closure means such as a plunger stopper. The chamber connects to the internal passage at the roof and connects to the stem bore in the floor of the chamber. These plungers also have a top end and a bottom end with at least one opening at or near the top and the bottom end and may have at least one port that allows the flow of the well contents. The chamber into the chamber connects to the flow passage to increase the flow rate and to facilitate even more rapid descent of the plunger. The preferred embodiment has a plurality of ports within the chamber, and may have additional ports near the top end.

The plunger stopper has a top end that has a shape similar to that of the roof, and in some cases, the upper chamber area, and has a stem attached to the bottom end that extends downward through and protrudes outwardly from an opening in the bottom end. When the stem engages the bottom well stop means upon descent, the closure means such as a stopper, is pushed upwardly against the roof of the chamber, thereby sealing off the inner passage and restricting the upward flow of liquids and/or gases from the chamber and the ports in order to build up pressure below the plunger.

The improved design of this closure means, or stopper, operates without springs or catches, yet still holds the stopper against the roof of the chamber. It also does not use long sucker rod, which are prone to bending, to unseat the closure means. Instead, the pressure build-up below the plunger keeps the plunger stopper engaged against the roof of the chamber. The plunger stays at or near the bottom well stop until the pressure in the tubulars above the plunger is reduced, or until the pressure below the plunger exceeds the pressure above the plunger. The simplified bore sealing means also reduces the amount of time needed for costly and time-consuming repairs and replacements and dispenses with the need for expensive and customized devices at the surface that unseat the prior art closure valves.

Referring first to FIG. 1, there is shown a well W for producing hydrocarbon gases and/or liquids from a subterranean reservoir R. The well may be of the horizontal or vertical variety. The plunger pump P is especially useful in wells where the gas pressure alone is insufficient to produce the flow of liquids or the significant flow of liquids at the surface. In these situations, hydrocarbons from such wells cannot be recovered except through the installation of considerably expensive submersible pump units that require daily inspection and maintenance. Similarly, in wells producing primarily gas, the gas production may be substantially impaired by liquids, whether hydrocarbons or salt water, which accumulate in the bottom of the well. In either event, it is desirable to remove liquids from the bottom of such wells without installing conventional pumping units. Typically, one or more well conduits extend from the subterranean reservoir R to the well surface WS. In the preferred embodiment, there is a casing string CS, at the upper end of which is a well head WH, and a tubular string T, also known as “tubulars.” Tubulars T is a generic term used to define the variety of tubes and tubular members, such as cement casings, conduits, and tubing and tubing string, which can also be referred to as the production string, which can be made from a variety of materials such as plastic, metal, and concrete. Tubulars line the well surface and can also be placed inside or on the outside of other tubulars. In any event, the tubulars are the well channels through which liquids from the subterranean reservoir R are raised to the surface. Near the bottom of the tubulars is a tubing stop means TS mounted in any suitable manner. The tubing stop means TS may be relocated by wire line or other operations at different depths as well conditions change. The tubing stop TS preferably incorporates a bumper spring B of some type for stopping downward movement of a plunger type pump unit P, which is slidably and sealably disposed in the tubulars T and which will be described in greater detail hereafter. At the well surface WS is a master cutoff or motor operated valve MV suitably attached to the tubing string T to entirely block the flow of gases and/or liquids from the tubulars T as desired. This arrangement further allows retrieval of the plunger pump P for inspection or repair. Above the valve V is a flow tee F and a lubricator L closed at its upper end by detachable end cap E. A bumper sub BS is usually placed therein with a spring (not shown) which is engageable by the plunger pump P when rising through the tubulars T to stop movement of the plunger P and to cushion the shock created thereby. Connected to the flow tee F is a production or pay line PL in which is installed a motor control valve MV. An electronic controller EC is provided for operating the control motor valve MV. The electronic controller EC is also connected to a tubing plunger sensor S for sensing the pressure within the wellhead WH. A plunger catching device PC may also be attached to the tubing string T above valve V. While not required, a rod could be used to unseat the closure means.

Initially, the plunger P is placed in the tubulars through the lubricator sub L. This is done by removing the cap E while the valve V is closed. Then the cap E is replaced, the valve V opened, and the plunger P is allowed to gravitate or fall to the bottom of the well through the tubulars T. Although the sealing means, such as a jacket 100 made of segments, e.g., 46, 47, 48, 49, is biased outwardly for sliding and sealing engagement with the interior of the tubulars T, there is a small amount of leakage around the outside of the jacket assembly 100 and through the edges of the sealing segments 46, 47, 48, 49. This permits the plunger P to fall under its own weight toward the bumper spring B that will arrest its downward movement. Other plungers of this invention that do not have a jacket, fall under their own weight. When this occurs, the motor valve MV is closed and a time sequence is initiated by the controller EC. Additional gases and/or liquids enter the tubulars T and the gas and/or fluid pressure begins to build. The controller EC is programmed to keep the valve V closed until substantial liquids have entered the tubulars T and sufficient gas pressure has built up within the well. The amount of time necessary will be different for every well and may change over the life of the well. After a predetermined amount of time, the controller EC opens the motor valve MV, which substantially reduces the pressure above the plunger P. Consequently, the accumulated gas pressure therebelow forces the plunger P, and the gases and/or liquids trapped thereabove, upwardly through the conduit or tubulars T, through the flow tee F, the valve V and the pay line PL for production of the well. As the plunger P is propelled upwardly through the tubulars T by pressure, it passes through the valve V, and is sensed by the sensor S and eventually movement thereof is arrested by a spring (not shown) in the lubricator sub L. When the plunger P is detected by the sensor S, a signal is transmitted to the controller EC that initiates closure of the valve V. Thereafter the plunger P is allowed to again gravitate or fall to the bottom of the well so that this cycle can be repeated.

However in wells that have very low pressures, the well need not be shut in (by closing the valve V) to allow the plunger to descend down the tubulars. This allows for a near continuous production. Additionally, in plungers with large diameter flow passages, such as 1 inch in diameter or greater, the plunger may also be able to descend down the tubulars without shutting in the well. Once sufficient pressure builds beneath the plunger, the plunger and the contents of the tubulars will be brought to the well surface.

In describing the specific embodiments herein which were chosen to illustrate the invention, certain terminology is used which will be recognized as employed for convenience and having no limiting significance. For example, the terms “upper,” “lower,” “top,” “middle,” “bottom,” and “side” refer to the illustrated embodiment in its normal position of use. The terms “outward” and “inward” will refer to radial directions with reference to the central axis of the device. Furthermore, all of the terminology defined herein includes derivatives of the word specifically mentioned and words of similar import.

Differential gas pressure operated pistons, also known as plungers, have been used in producing subterranean wells where the natural well pressure is insufficient to produce a free flow of gas, and especially liquids, to the well surface. A plunger lift system typically includes tubulars placed inside the well conduit, which extend from the reservoir(s) of the well to the surface. The tubulars have a well valve and lubricator at the top and a tubing stop and often a bumper spring or other type of spring assembly at the bottom. The cylindrical plunger typically travels between the bottom well stop and the top of the tubulars. The well is shut in for a selected time period that allows pressures to build up, then the well is opened for a selected period of time. When the well valve is opened, the plunger is able to move up the tubulars, pushing a liquid slug to the well surface. When the well valve is later closed, the plunger, aided by gravity, falls downwardly to the bottom of the tubulars. Typically, the open and closed times for the well valve are managed by a programmable electronic controller.

When the plunger is functioning properly, liquids accumulate and stay above the plunger and pressurized gases and/or liquids below the plunger are blocked from flowing up, around, and through the plunger. As a result, the plunger and accumulated liquids are pushed upwardly.

The improved stopper assembly that is housed in a chamber is typically located in a modified end cap and seals off the inner passage in a simplified manner. The stopper stem and stopper head is pushed up into the chamber when the plunger bottom contacts the well stop means, and the stopper is held up against the opening of the passage by the fluid and/or gas pressure below the plunger.

FIG. 1A shows an embodiment of plunger according to this invention that is descending in the production tubulars T, with the closure member 600 in the open position. The fluids 912 in the tubulars are able to enter the chamber 510 through the ports 701, 702 and flow into the inner passage 460 and out an opening 720 in the top of the plunger body. Of course the opening may be near located elsewhere, near the top.

FIG. 1B shows an embodiment of plunger according to this invention in the production tubulars T, with the closure member in the closed position. The fluids 912 in the tubulars are still able to enter the chamber 510 through the ports 701, 702 and flow into the chamber below the closure member, but cannot exit through the inner passage 460 as the closure member has closed off the communication 525 between the chamber and the inner passage.

This simplified and improved design dispenses with the need for complicated moving parts which to actuate the closure means, and eliminates the need for expensive equipment at the well head which is used to unseat the closure means.

Referring now also to FIGS. 2-25, the drawings show a plunger, which is used in a gas/fluid lift system in the tubulars T of wells that produce both liquids and gases under variable pressure. Referring now to the drawings in detail, FIGS. 1, 2, 18, and 20 show a plunger that has a body that is slidingly engageable within the well tubulars T. The body is typically made of rigid material, such as arty type of metal or metal alloys, rigid plastics and polymers, ceramics, and the like, with the preferred embodiment being made of stainless steel. In an embodiment, the body has an inner core 10, for support and for inner sealing. The core 10 may also be known as a mandrel, and may be solid or hollow. The core is typically substantially cylindrical and typically has the smallest diameter of the plunger body.

As in FIG. 2, there is a flexible jacket assembly 100 surrounding or mounted about the core 10. The preferred embodiment has four segments 20, 21, 22, and 23, which collectively form a flexible jacket assembly 100. Of course, fewer or more segments can be used to form the jacket assembly. These segments 20, 21, 22, and 23, are made of a relatively rigid material, such as those known in the art, like metal, hard rubber, plastic, graphite, etc., and typically have a relatively smooth outer surface, due to the die cast molding of the segments, and/or polishing of the segments, for sliding and sealing contact with the walls of the well tubulars in which the plunger P is to be used, such as the inner walls of the tubulars T in FIG. 1. Referring now to FIGS. 2, 3 and 4, each segment typically has a substantially convex outer shape 30 and a substantially concave inner surface 32, like that of a semicircular arch. In an embodiment, each segment 20-23, or 46-49 (see e.g., FIGS. 5-8 and 35-36) has substantially the same width and curve so that several segments can be placed side by side to form a flexible jacket assembly 100, which is mounted around the core 10, such as by upper and lower retaining rings 150 and 160, respectively. The retaining rings 150, 160, limit the outward radial movement of the jacket assembly, and may be secured by one or more set screws 415. The inner surface of the jacket assembly 100 is separated from the core 10, unless it is pushed to its most inward position.

The sealing segments 20, 21, 22, 23, which collectively make up the jacket assembly 100, are typically held in position around the core 10 of the plunger body by retaining means such as an upper retaining ring 150 and a lower retaining ring 160, which slip on over the core 10, with the upper retaining ring usually abutting the collar 410 of a fishing part 420. As in FIG. 19, the top end 400 of the core 10 is also typically substantially cylindrical and has means such as threading, i.e., a helical or spiral ridge which can be used to removably or securably attach, by screwing, into or onto another part. Alternatively, there may be drilled or threaded holes in both the plunger body and the part, to be secured other parts of the plunger may be connected by threads, welding, soldering, pins, screws or a combination thereof. Other parts include plunger parts, plunger accessories, or other oil field components or tools.

The preferred embodiment has a upper end fishing piece 420 which is typically threadingly connected 430 near the top end of the core 400 and has a head 425 located above a fishing neck 424 of a reduced diameter that is removably attached to the top end 400 and may also be secured with a set screw, e.g., 415. The fishing piece 420 may also have a wrench flat 423, to assist in loosening or tightening. Alternatively, the fishing piece or part 420 may be tooled into the core 10. The lower retaining ring usually abuts an end cap 140. The bottom end 426 of the core 10 typically has means such as threading 435 to attach other parts. In the embodiment of FIG. 18, a plug or end piece 140 is threadedly connected to corresponding threads 435 on the lower end of the core 10, and may have a tapered end 141. The cap may be provided with wrench flats 142 for aiding in the engagement or disengagement of the threaded connection, and a set screw (not shown) may be tightened when the cap is fully engaged as to prevent accidental loosening or disengagement. Alternatively, the end cap 140 may be tooled into the bottom end 426 of the core 10.

The upper and lower ends of each of the segments may also have notches across the ends as in 21 c, 23 c, or recessed ends such as in 21 d, 23 d, which cooperate to fit under the retaining rings 150, 160. This limits the movement of the jacket assembly 100 radially inwardly and outwardly from the core 10. The upper and lower ends of the segments may also be inwardly tapered as in 20 a, 21 a, 22 a, 23 a, so that when the segments engage a restriction in the well tubulars T, the segments will be forced toward their most inward position. This allows the plunger to overcome the restriction and to pass through the restricted area. In their innermost position 290, the segments, e.g., 20-23 and 46-49, have a diameter less than that of any restriction to be encountered in the tubulars. Referring now to FIGS. 1 and 2, the jacket assembly also has the largest diameter 300 of the plunger when the jacket assembly 100 is in its most radially expanded position 300, when it sealingly engages the tubulars. Referring now to FIGS. 1, 3, and 4, the jacket assembly 100 is also slidingly and sealingly engageable within the well tubulars T, based upon the pressure effected by the flow path 200 between the underside of the jacket 100 and the core 10 by the gas and liquids that move upwardly between the segments 20, 21, 22, and 23, and based upon the outward biasing force of the jacket assembly against the tubulars T.

Typically, the segments are substantially rectangular 25. However, the segments 20, 21, 22, 23, and 46, 47, 48, 49, may be a variety of geometric shapes, sizes, and dimensions, as long as they are able to cooperate to surround the core or to form a jacket assembly 100. One such variation of segments 46, 47, 48, 49 of the preferred embodiment are shown in FIGS. 5, 7-15, 18, 20, and 35. One of the segments 48 is in inner and outer perspective views in FIGS. 5, 7, 8, 9, and 10, and cross-section in FIGS. 11, 12, 13, and 15. FIG. 6 is an upper end view of the segments 46-49. FIG. 14 is a sectional view of the segments 46-49 at section B-B, in their most inward position. Each of these segments 46, 47, 48, 49, is provided with a convex, or substantially convex outer surface, 51, 52, 53, 54, respectively. The inner surfaces of the segments are substantially cylindrical in shape, e.g., 46 a, 47 a, 48 a, 49 a. The segments of the preferred embodiment further have sides which have a tab 60 or slotted 61, 67 portion, preferably with a tab 60 on one side and a slot 61, 67 on the opposing side, as in FIGS. 5, 7, and 8. For example in FIG. 5, segment 48 has a tab 60 that is engaged with slot 61 of segment 49. See also segments 46 and 47 in FIG. 14, with tabs 64, 66, respectively and slots 63, 65, respectively. The cross-section of segments 46, 47, 48, 49, as in FIG. 14, show that when the mutually engageable tabs 60, 62, 64, 66 are interconnected with the slots 61, 63, 65, 67 located on the sides of the adjacent segments, that a circumferential jacket assembly 100 is formed. In FIGS. 6, 8, and 9, these tabs, e.g., 60, and slots, e.g., 67, have stepped areas so that a portion of a tab 60 a overlaps an inset portion of a corresponding slot 67 a, 67 b. The overlapping is accomplished with opposing surfaces, e.g., 67 a and 60 a, which are slidably engageable with the opposing surfaces of the adjacent segments 46-49, and which guide the segments inwardly and outwardly between their innermost and outermost radial positions. These overlapping, opposing, sealing surfaces are planar surfaces which are tangentially disposed relative to a cylinder whose axis corresponds with the axis of the core 100 of the plunger body about which the segments are disposed. The overlapping surfaces further minimize leakage from the flow path 200 of FIGS. 16, 17, between the core and the segments, and therefore assist in inner sealing.

The upper and lower ends of these segments may also be inwardly tapered as at 51 a, 52 a, 53 a, 54 a, and 51 b, 52 b, 53 b, 54 b, respectively, so that when the segments engage a restriction in the well tubulars, the segments will be forced inwardly to allow the plunger to pass through the restriction. In the preferred embodiment, the upper ends of each segment have a semicircular notch 70, 72, 74, 76, as do the lower ends of such segments 71, 73, 75, 77, which slidably fit under the lugs, e.g., 153, 163, 164 of the retaining rings. See FIGS. 18, 19.

The preferred embodiment further has segments wherein the inner surface or underside, e.g., FIG. 7, 16, possess at least one finger 120 which is preferably made of rigid material, such as metal, stainless steel, plastic, hard rubber, graphite, and the like. The rigid fingers 120 of the exemplary embodiment are made of metal and are an integral part of the segment 46, 47, 48, 49, which is molded. The exemplary embodiment has three fingers 120 on the underside of each segment. See, for example, FIG. 7. Preferably, there is a plurality of rigid fingers on each segment underside, with the preferred embodiment, e.g., FIGS. 4, 7, 19, having three such fingers 120 on the underside of each segment 32, 63, respectively. The fingers 120 of each segment protrude radially inward toward the core 10 and are parallel and horizontally aligned with the fingers 120 of the adjacent segments to collectively cooperate to encircle the core 10, and serve as part of the internal sealing means. The fingers 120 and core 10 are typically separated by space, or a flow path 200 unless the fingers are pushed to their most inward position. If the core 10 also has grooves, e.g., 12, 14, 16, the fingers 120 on the underside of the segments 46, 47, 48, 49 are adjacent to and aligned with the grooves 12, 14, 16, and the fingers 120 fit into the grooves, 12, 14, 16. See FIGS. 3, 19. Where both fingers and grooves are present, there is an increased surface area between the inner surface of the segments and the core, which energizes the segments and pushes the segments outwardly to cause an external seal with the tubulars. Typically during operation, the fingers 120 and core 10 or core grooves 12, 14, 16, are separated by a space, or flow path 200.

As in FIGS. 3, 7, 13, each finger 120 is defined by top 120 f and bottom side surfaces 120 b. The fingers 120 may be in a variety of geometric shapes. For example, the fingers 120 may have a cross-section such as that of a V-shape, wherein the top and bottom sides converge (not shown), or conversely the side surfaces may diverge with respect to one another (not shown). In the preferred embodiment, the fingers 120 also have an inner surface 120 d, which is a curved concave shape, which is complimentary to the shape of the core 10. However, the inner surface of the finger 120 could also be semicircular in cross-section, with a convex inner surface (not shown). Many other variations and combinations thereof are also possible. Further, the finger has first 125 a and second side edges 125 b which are flat and angularly aligned with the first and second adjacent side edges of the segment, e.g., 48 a, 48 b, respectively. The elevation of the fingers 120 may vary. In the embodiment having a grooved core 12, 14, 16, the elevation of the fingers 120 may be at least as great as the depth, e.g., 18 b of the groove, e.g., 12, 14, 16, 18, or conversely, less than the depth of the groove 12, 14, 16. However, the fingers 120 must be of a narrower width than that of the corresponding groove, so the fingers 120 can fit into such grooves, e.g., 12, 14, 16. See FIGS. 18, 19. Further, the fingers 120 may be of a uniform or variable elevation, shape, and width with respect to one another.

Now referring back to the fingers on the underside of the segments, in the preferred embodiment, the top and bottom side surfaces 120 f, 120 b of the finger 120 has an angle of substantially 90 degrees, relative to the outer surface of the core 11, and has an inner surface 120 d which is substantially parallel to the outer surface of the core 10. The finger 120 of this design has a square or rectangular cross-section. See, e.g., FIGS. 5, 18, 20.

Alternatively, the fingers may be located on the surface of the core 11, and would be referred to as “bands” (not shown). The core may have one circumferential band, or a plurality of circumferential bands. In this case, the bands have corresponding elements and features equivalent to those found in the fingers. The bands may be found in an embodiment with or without corresponding furrows on the underside of the segments (not shown). In this case, the furrows have corresponding elements and features equivalent to those found in the grooves of the core. The underside of the segments may have one furrow, or a plurality of furrows, which collectively form a circumferential furrow. When there are both bands and furrows present (not shown), the bands on the surface of the core 11 (not shown) fit into the corresponding furrows on the underside of the segments (not shown). The bands may be a variety of shapes and widths, similar to those described for the fingers. Preferably, the band has a flat bottom side and a flat top side and a curved outer surface. The bands may also have a variety of elevations, and may be at least as great or less than the depth of the furrow (not shown). Similar to the plurality of fingers and grooves, a plurality of bands and/or furrows create a tortuous path of flow for liquids and gases and an increased surface area between the undersides of the segments and the core which would energize the segments and push the segments outwardly to cause an outer seal with the tubulars. Further, a plurality of bands and/or furrows also provides a tortuous path of flow and effects an inner turbulent seal and retards the upward flow of liquids and gases and causing an increase in pressure below the plunger. Similar to the fingers and grooves, the biasing means may be placed between the core and the segments. Also similarly, there may be at least one blind hole in each band that accommodates a biasing means, discussed below, under each segment. The biasing means may also be disposed between the band and the furrow (not shown). Further, at least one furrow in each segment may have a blind hole that accommodates the biasing means with the biasing means being disposed between the band and the furrow (not shown).

The core 10 of the plunger body in FIGS. 16, 17, 18 may also possess internal sealing means such as one grove or a plurality of longitudinally spaced circumferential grooves 12, 14, 16, 18 which are defined by recessed surfaces that are interspersed between the ungrooved sections of the surface of the core 11. There is also an inner turbulent sealing effect, FIG. 4, when the embodiment has an ungrooved core and at least one, or preferably a plurality of fingers, e.g., 120 that project inwardly toward the core 11. There is an even more dramatic inner sealing effect where the embodiment has grooves 12, 14, 16 as well as projections, e.g., 120.

Each groove, e.g., 12, 14, 16, or 14, 16, 18 is defined by a recessed surface, e.g., 18 b and upper and lower side surfaces, e.g., 18 a and 18 c, respectively. In the preferred embodiment, the lower surface portion 18 b has an angle of substantially 180 degrees, relative to the outer surface of the core 11, and have upper and lower portions 18 a, 18 c, that have an angle of substantially 90 degrees, relative to the outer surface of the ungrooved core 11 a. The core of this design has a square or rectangular cross-section, see, e.g., FIG. 16. The preferred embodiment of the plunger has a core 10 which includes a plurality, preferably three, of longitudinally spaced circumferential grooves, e.g., 12, 14, 16, that divide the peripheral surface of the core 11 into a plurality of outer surface sections, e.g., 11 a, 11 a. Again, due to the necessity for clearance between the plunger P and the tubulars T which allows the plunger to fall or gravitate to the bottom of the well, a flow passage is formed between the jacket and the tubulars, and some of the gas below the plunger P will flow up between the plunger P and the tubulars T, as well as up into the plunger beneath the jacket assembly and the core. As shown in FIGS. 16, 17, for illustration purposes, the gas also enters into the flow path 200 between the segment 48 and the core surface 11, 11 a, a first portion F.sub.1 of the gas flows along the surface of the ungrooved core 11 a and the segment underside 63, and a second portion F.sub.2 flows down into the groove, e.g., 16, 18 and recessed surface, e.g., 18 b. The four right angles at each corner, 13 a, 13 b, 13 c, 13 d, and along the recessed surface 18 b and the top 18 a and bottom sides 18 c of the groove 18 cause the first portion F.sub.1 and second portion F.sub.2 of flowing gas meet at substantially a right angle at the corner 13 a, creating a turbulent flow region T.sub.1, that inhibits liquid flow downward into the groove and inhibits gas flow upward out of the groove. The gas flowing up along the plunger core surface 11, 11 a dissipates energy at each successive groove, e.g., 16, 14, 12. Alternatively, the grooves may be located in the underside surfaces of the segments, e.g., 46-49 (not shown). In that situation, the grooves would have corresponding elements and features equivalent to those found in the grooves, e.g., 12, 14, 16.

The groove may also be in the form of a spiral, or conversely in a variety of geometric shapes, and, for example, may have a cross-section such as that of a V-shape, or top and bottom sides that converge or diverge with respect to one another, or a semicircular cross-section (not shown). Many other variations are also possible. For example, the depth and/or length of the recesses, e.g., 18 b, may be variable, as well as the length of the body sections 11 a between the recesses. Further, the grooves, e.g., 12, 14, may be of a uniform or variable depth, shape, and width, with respect to one another.

As best seen in FIGS. 16, 18, the preferred embodiment may also have biasing means, which are typically springs 190, disposed between the core 10 and the underside or inner surface of the segment, which biases the segments, e.g., 46, 47, 48, 49, outwardly from the core 10. The biasing means may take the form of a helically wound spring 190 or leaf spring or other member which has the ability to rebound or recoil after being compressed. Further, the core 10 may possess a blind hole 180, or a blind hole 182 may be present in the core groove 185, e.g., 12, 14, 16. Preferably there are two biasing means, e.g., 190 between each segment, e.g., 46, 47, 48, 49 and the adjacent area of the core 10 or core groove, e.g., 12, 14, 16. The biasing means 190 are preferably placed about midway across the width of the segment and at places along the length of the underside that leave the segment balanced against the core 10. The blind holes, e.g., 180, 182, accommodate and hold the biasing means, e.g., 190 in place. The finger of the preferred embodiment may also have a blind hole 185 that accommodates a biasing means, e.g., 190. Preferably the embodiment has a blind hole in both the core 180 or core groove 182 and the underside of the adjacent segment 185 (not shown) or finger 120. This design minimizes the risk of loss of the biasing means 190.

Referring to FIG. 1, the gas below the plunger P must have sufficient pressure to overcome the weight of the plunger P and a liquid slug LS on top of the plunger P, and the pay line PL pressure, in order to move the plunger P up the tubulars T. Due to the necessity for clearance between the plunger P and the tubulars T which allows the plunger to fall or gravitate to the bottom of the well, a flow passage is formed between the jacket 100 and the tubulars T, and some of the gas below the plunger P will flow up between the plunger P and the tubulars T, as well as up into the plunger beneath the jacket assembly 100 and the core 10. As shown in FIGS. 16, 17 once the gas and/or liquids enter into the flow path 200 between the segment 48 and the core surface 11, 11 a, a first portion F.sub.1 of the gas flows along the surface of the core 11 and the segment underside 63, and a second portion F.sub.2 flows down and around the raised finger 120. The four right angles at each corner of the finger, 120 a, 120 c, 120 e, 120 g, and along the surfaces of the bottom 120 b and top sides 120 f and inner surface of the groove 120 d, cause the first portion F.sub.1 and second portion F.sub.2 of flowing gas to meet at substantially a right angle at the corner 120 e, creating a turbulent flow that inhibits liquid flow downward into the areas of the segment between the fingers which have lower elevations and inhibits gas flow upward out of the segment area between the fingers. The gas flowing up along the plunger core surface 11, 11 a dissipates energy at each successive finger, e.g., 120. There is an even more dramatic inner sealing effect where the embodiment has some grooves 12, 14, 16 in the core 10, as well as projections, e.g., 120, FIGS. 16, 18.

The sealing segments 46-49 are mounted around the core 100 of the plunger body and are preferably held in place by a retaining means such as an upper retaining ring 150 and a lower retaining ring 160. See FIGS. 2, 4, 18, 19. The retaining rings 150, 160 are substantially cylindrical and have a hollow inner surface of slightly larger diameter than the core 10 and a shape that corresponds to the shape of the core 10. The retaining rings also have first 151, 161 and second 152, 162 ends, with the first ends 151, 161 having a plurality of lugs positioned next to the segments, and the seconds ends being positioned on the opposite side of the segment ends. Preferably the retaining rings 150, 160 have a plurality of lugs, e.g., 163, 164, preferably four, which are spaced at ninety degree intervals around the retaining rings 150, 160, and which are positioned to protrude inwardly toward the segments and are oriented to engage the notches 70, 72, 74, 76 at the upper ends of the segments 46, 47, 48, 49, as in FIGS. 5, 6, and the lower ends of the segments, e.g., 71, 73. The retaining rings 150, 160 may also serve to hold the fingers 120 in position over the grooves, e.g., 12, 14, 16, 18, in the core 10. The upper retaining ring 150 is slipped over the core 100 of the plunger body and is positioned adjacent to the segments, 46-49, and may also be adjacent to the shoulder 410 of the fishing piece 420, which may be tooled into the top end of the core 10, or removably attached to the body such as by threading 430. The retaining 150, 160 rings may be held in place by a set screw 415, which is screwed into a drilled hole 402 in the core 10. See FIGS. 18, 19. Similarly, the lower retaining ring 160 is slipped over the core 100 of the plunger body and is positioned adjacent to the segments, 46-49, and may also be adjacent to the end cap 220, which may be tooled into the bottom end of the core 10, or removably attached to the body such as by threading 225, and may also have corresponding lugs. Alternatively, the segments, e.g., 21, 23, 48 may have a slotted, e.g., 21 c, 23 c or notched top, e.g., 70 and bottom ends, e.g., 71 which slidably fit under the retaining rings, and limit the outward radial movement of the segments, e.g., 21, 23, 48. See FIGS. 4,8.

Further, in an embodiment having a grooved core, e.g., 12, 14, 16 and fingers 120, and upper 150 and lower retaining rings 169, the edges of at lease one the groove, typically the uppermost or lowermost, e.g. 16, of the core 10 is preferably angularly reduced to allow installation of the segments 46, 47, 48, 49 underneath the upper retaining ring 150. See FIG. 19. Further, the top or bottom edge 12 a of the lowermost or topmost groove, e.g., 12 of the core is angularly reduced 12 k to allow installation of the segments with fingers 120 underneath the lower retaining ring 160. Of course the fingers 120 of the segments, e.g., 46-49, may also be present in plungers with grooved cores 12, 14, 16, with fingers interspersed in the core grooves. In that case, at least one outer edge of one of the grooves, e.g., 12, or grooves, e.g., 12, 14, 16, is angularly reduced to allow installation of the segments with fingers 120 underneath the retaining rings, e.g., 150, 160.

Referring now to FIGS. 1, 20-25, the operation of an additional embodiment of a plunger will be explained. FIGS. 20-25, illustrate an alternate embodiment of the invention that in many respects is the same as the embodiments of FIGS. 1-19. Similar to the previous embodiments, the plunger of FIGS. 20, 23, 24, and 25 has a body with a core 10, but also has areas defined as a top end 400, and a bottom end 500. The top end 400 has threading 430 to which additional parts can be attached. In this embodiment, a separate piece, such as a fishing part 420 is threadingly connected to the body at a threaded connection 430. The top end fishing piece 420, like some of the previous embodiments, is provided with a head area 425 and a reduced neck 424 for engagement by a fishing tool if required. The bottom end 500 is provided with an external thread 435 to which additional parts can be attached such as a modified end cap 220 with a corresponding internal thread 221, provides a threaded connection between the body and the end cap 220. The modified end cap 220 includes an enlarged chamber portion 510. The plunger is also provided with an inner passage 460 which may extend partway through or through the entire body and plunger, a chamber 510, and a closure member 600. The major difference between the plunger of FIGS. 2 and 18 and the previously described features of FIGS. 2-19 is the inner passage 460 and the chamber 510 and closure member 600. Like in the previously described embodiments, the plungers of FIGS. 20-25 is provided with an outer seal means made up of a plurality of segments, e.g., 46, 47, 48, 49, or 20-24, which are substantially similar, if not identical, to the corresponding elements in the embodiments of FIGS. 2-19. Retaining rings 150 and 160 hold these segments 46, 47, 48, 49, or 20-24, collectively the jacket assembly 100 in place but permit yet limit outward radial movement between an innermost position 290, in which the exterior cylindrical surfaces thereof lie has a diameter less than that of any restriction to be encountered in the tubulars T with which it is to be used, and an outermost position 300 in which the exterior cylindrical surfaces, e.g., 46, 47, 48, 49 slidingly and sealingly engage the walls of the tubulars T in which the plunger P is to be used. Biasing means such as springs 190, bias these segments toward their outermost position 300. The unique circumferentially and mutually engageable tabs and slots and the overlapping opposing tangentially disposed planar surfaces provided by stepped areas, as in FIGS. 5, 6, 8, 14 thereon allow radial inward and outward movement while limiting leakage and erosion caused thereby.

As in the embodiments shown in FIGS. 2-19, the body of the plunger also includes an internal sealing means, such as the inner surfaces of the segments, which may also have rigid fingers 120 projecting inwardly. Or alternatively, the raised surfaces may be in the form of a rigid band on the surface of the core 11 (not shown). Preferably, each segment, e.g., 46-49 has three fingers 120 on the underside of each segment, which protrudes radially inward toward the core 10. The fingers 120 of each segments, e.g., 46-49 are parallel and horizontally aligned with the fingers of the adjacent segments so the fingers collectively cooperate to encircle the core 10. As in the previous embodiments, the preferred internal sealing means also includes a core 10, wherein the surface 11 is grooved, e.g., 12, 14, 16. Where there are both grooves 12, 14, 16, in the surface of the core 11 and fingers 120 on the segments 46, 47, 48, 49, the fingers 120 are adjacent to and fit into the grooves 12, 14, 16, in the core. The fingers 120 are typically separated from the core 10 unless the fingers are pushed to their most inward position. Typically during operation, the fingers 120 and core 10 are separated by a space, or flow path 200. This arrangement of grooves and/or finger projections (or a band located on the core 10, not shown) creates a tortuous path of flow that effects an inner turbulent seal.

The chamber 510 that houses the closure means, such as a stopper 600, is an enlarged area within the end cap 210, and the body provides at least one side wall 918, at least partially surrounding the chamber. As previously mentioned, the end cap 210 is threadingly connected to the lower plunger body portion 500 at the threaded connection 435. The chamber 510 has a roof 520 at the upper end which may be inwardly tapered 545 below the roof 520, with an opening 525 in the roof which communicates with the upper inner passage 460 and a floor 550 at the lower end with an opening in the floor into a bore the floor may communicate with a bore which houses a stem 630 attached to the closure means. Furthermore, there is an opening 560 at the end of the plunger stem bore passage 560 at the bottom of the end cap 570. When the closure means rests upon the chamber floor at least part of the time and is in the open position, which allows fluid and/or gas to enter the inner passage, the stem protrudes downward 670 from the body of the plunger. In one embodiment, the roof 520 of the chamber 510 is substantially horizontal and has edges or walls that correspond with the shape of the upper side of the closure means. Additionally, the walls 918 of the chamber may be straight, angled, or curved to correspond with the shape of the closure means. Further, a stopper 600 with a head may be used as the closure means. The top end of the head may be dome shaped, like the roof of FIGS. 20 and 23. In that case, the floor is nonparallel to the roof. Alternatively, the roof 520 may be triangular in cross-section and the head of the stopper is correspondingly cone-shaped or triangular, like that of FIGS. 24-25.

In an embodiment, the plunger has a chamber that is circular in cross-section, a floor that is flat, and a flat roof, with the floor being parallel to the roof. See e.g., FIGS. 37-38. Further, in an embodiment, the stopper has a triangular top end. See FIGS. 24-25, and FIGS. 26-29, and FIGS. 31, 33, and 34.

In a further embodiment, the plunger has a chamber with a floor that is flat, and a dome shaped roof, like that of FIGS. 20 and 23, and a stopper that has a semicircular or dome shaped top end, like that of FIGS. 20 and 23. There are also other variations of additional shapes which the chamber roof and chamber floor could possess, such as a flat roof with straight chamber walls and a curved or flat floor, and corresponding variations of the shape of the first end and second end of the stopper, such as a flat top end and a circular bottom end (see FIG. 23), which could also be operable.

The roof 520 of the chamber 510 is further connected to a downwardly facing and tapered seating surface 530. The area below the seating surface 530 is also provided with an area partially defined by a slanted or tapered ramp area 545 below the seating surface 530. The seating surface 530 of the preferred embodiment is sized and designed to receive and guide a plunger stopper closure member 600 albeit rounded, half-sphere, or ball-type, upwardly to the seating surface 530 in the roof 520. The plunger stopper 600 has a head 615 with a top end 610 and a bottom end 630, wherein the bottom end of the stopper is substantially curved 635. Conversely, the bottom end of the stopper may be substantially flat 630. A stem 650 is attached to the bottom end 630 of the head 615. Alternatively, the top end 610 of the plunger stopper 600 may further have a stem 670 that is attached to the top end 610 of the head 615. This stem 670 will be pushed up into the inner passage 460 above the chamber 510, when the bottom end 570 of the plunger hits the bottom well stop means to further ensure closure of the opening 525 into the passage 460. (See FIGS. 24, 25). Under certain conditions, the stopper 600 is moveable between the open position of FIG. 20, in which fluid and/or gas flow is permitted into the inlet ports, e.g., 700, 702 in the end cap 220 through the chamber 510 and into the passage of the body 460, through the hole 525 in the roof 520, and out through the outlet ports, e.g., 715, 716, 717, 718 in the top end. In FIG. 23, the stopper 600 is in a closed position in which the fluid and/or gas flow through the chamber opening 545 into the passage 460 of the plunger body is blocked by the top 610 of the stopper 600. In the open position, the stem 650 extends downwardly through the opening 555 in the hole in the floor 550 of the chamber 510 into the bore 540 in the bottom of the end cap 560, and protrudes 670 from the lower end of the plunger body 570, when the plunger is descending through the tubulars T, or at the surface once the motor valve MV has been opened. When the stem 655 and then the bottom end of the plunger reach the bottom of the well, or some type of bottom well stop or well stop means TS, the stem 650 and stopper head 615 is forced or pushed upwardly until the top end of the head 610 is seated against the seating surface 530 of the roof 520 of the chamber 510.

The fishing part that is attached to the top end also has an inner passage 460. In one embodiment, the inner passage 460 also has an opening 720 at the top end of the plunger. As previously discussed, the fishing part 420 may also have a plurality of outlet ports 715, 716, 717, 718, or axial inner passages, disposed around the sides of the collar 410 of the fishing piece 420, in addition to, or instead of the opening at the top end 720. Preferably, there are four radial ports, e.g., 715, 716, 717, 718 that are spaced along the cylindrical axis of the collar at about 45 degrees from each other.

Similarly, there are preferably a plurality of radial ports located along the cylindrical axis of the end cap 220. In an embodiment, the ports are about 45 degrees from each other 700, 701, 702, and 703. The location of the inlet ports, e.g., 700, 702 in the chamber wall 511 of the end cap 220 are especially important. The ports 700, 702 are preferably located so that the inside openings of the ports 710, 712 into the chamber 510 are located above the top end 610 of the plunger stopper head 615 when the stopper 600 is in its downward position. Furthermore, these inlet ports are preferably located so that the inside opening of the ports 710, 712 will be below the bottom end 630 of the stopper head 615 when the stopper is in its upward position, closing the inner passage 460. This placement of the inlet ports assures the bypassing of liquids through the chamber passage 510 and into inner passage 460 as the plunger falls in the tubulars T.

The plungers of the embodiments of FIGS. 20-38 also operate much as the plunger embodiment of FIGS. 2-5 and 6-19, and may be described with reference to FIG. 1. Like the plunger P of FIG. 1, and 2-19, the plunger of FIGS. 20-38 may be placed in the tubing string T and allowed to fall or gravitate to the bottom of the well W for producing the subterranean formation F thereof. However, it will fall more rapidly due to the inner passage 460. When the bottom end of the plunger 570 reaches the well stop or stop means, the stem 650 of the closure means such as the stopper 600, and the head member 615 are pushed upwardly toward the roof and to the seating surface 530 and the closure means or stopper 600 is seated against the roof 520. When the plunger P reaches the bumper spring BS at the bottom of the tubulars, the weight of the plunger pushes against the well stop TS forcing the stopper stem 650 and head 615 in an upward direction. As soon as the closure member enters or obstructs the flow path of valve passage, the top end 610 of the stopper 600 then proceeds past the ramp area 545 and up into the seating surface 530 in the roof 520. Once the stopper 600 is seated to assume its closed position seated, the flow of liquids into the chamber through the inlet ports, e.g., 702, 710 will flow up into the chamber 510 and against the second end of the plunger head 630 will cause the stopper to assume and maintain its closed position against the seating surface 530 as illustrated in FIGS. 23, 25. At this point, the bypassing of fluid through the passage 460 is blocked and gas pressure is allowed to build up just as with plunger 1 and 2 of the embodiment illustrated in FIGS. 24 and 5-19. After a preselected, predetermined period of time, the control valve MV at the surface is opened by the controller EC and the gas pressure built up in the well causes the plunger and any well liquids accumulated in the tubulars T thereabove to be elevated to the surface and produced through the production or pay line PL. Once the plunger is detected by sensor S and the control valve V closed by the controller EC, pressure is equalized in the area of the lubricating sub E. When that occurs the plunger stopper 600, due to its own weight, falls back down and reassumes its open position of FIG. 20-24, and 38. This opens the inner passage 460, allowing the plunger to descend to the bottom of the well W to repeat the cycle.

Of course the concept of the novel bypass and chamber with a closure member such as a stopper can be utilized in downhole plungers of any type and design, with or without pads. FIGS. 26-39, for example, are additional types of plungers in which Applicants' invention may be incorporated. The plunger of the embodiment of FIGS. 26-39 operates much as the plunger embodiment in FIGS. 20-25, as previously described.

The plungers in FIGS. 26-30 are known as spiral plungers, FIG. 31 shows a Teflon coated spiral plunger that reduces the friction between the plunger and well tubulars. FIG. 32 is a plunger with pads, FIG. 33 is a brush plunger, and FIG. 34 is a wobble washer plunger where individual washers which move around the mandrel of the plunger. The plunger of this invention, may also have at least one external pad disposed about a portion of the plunger body, with or without a grooved mandrel. See e.g. FIGS. 35-36.

The spiral plungers of FIGS. 26-32, and the washer plunger of FIG. 34 also provide a labyrinth type external seal against the tubulars, and the brush plunger also provides external seal against the tubulars.

The plungers of FIGS. 35-36 have pads that provide an external seal against the tubulars and a flow path between the pads and the mandrel. The sealing features of the plungers of FIG. 35 is like that of the plunger and elements of FIGS. 5-18, as previously described. And, the sealing features of the plunger of FIG. 36 is like that of the plunger of FIGS. 2-3, as previously described.

The internal bypass and flow passage of plungers of FIGS. 29-38 function similarly and have common elements. For example, the plungers of FIGS. 26-34 have a body, and areas defined as a top end 400, and a bottom end 500. They also have an inner passage 460, chamber 510, and closure means within the chamber, and ports that open into the chamber. The flow passage in these plunger also has an opening 720 at the top of the plunger body.

Spiral plungers, brush plungers, pad plungers, and wobble washer plungers are well known in the art. These plungers are often used in well tubulars to clean debris or buildup from the inside or well tubulars and/or to prevent such build up. Applicants have improved the operation of such plungers by incorporating an inner passage, a chamber, and a closure means within the inner chamber of such plungers. The operation of other plungers can also be improved by incorporating Applicants' improvements.

The plunger of the embodiment of FIGS. 26-38 also operates much as the plunger embodiment of FIGS. 20, and 23-25. Like the plunger P of FIG. 1, and FIGS. 20-25, the plunger of FIGS. 26-38 may be placed in the tubing string T and allowed to fall or gravitate to the bottom of the well W for producing the subterranean formation F thereof. These plungers will fall more rapidly due to the inner passage 460 than their counterparts that do not have an inner passage. The inner passage is typically positioned within the center of the plunger body, and may extend the entire length of the plunger, or nearly the entire length of the plunger.

Similar to the previous embodiments, the plunger of FIGS. 35-38 have a body, and areas defined as a top end 400, and a bottom end 500. See FIGS. 37-38 The body is typically made of rigid material, such as any type of metal or metal alloys, rigid plastics and polymers, ceramics, and the like, or other materials used or known by one skilled in the art, with the preferred embodiment being made of stainless steel to resist corrosion.

The wall thickness 900 of the plunger body varies upon the material used. It is also important to note that in plungers that do not have a grooved mandrel or a body with external spirals 902, the bore area that houses the inner passage 460 can be enlarged since the mandrel or body is not being decreased in thickness to make grooves.

In an embodiment, a fishing part can be included, but is not required. The fishing part can be internal or external. The fishing part may be a separate piece 420 connected to the body, or may be a part of the body. The top end fishing piece 420, like some of the previous embodiments, is provided with a head area 425 and a reduced neck 424 for engagement by a fishing tool if required. See FIGS. 35-36. Alternatively, the plunger may have an internal modification 420 a to facilitate fishing of the plunger from the tubulars. See FIGS. 37-38.

The plunger is also provided with an inner passage 460 which may extend partway through or through the entire body. In an embodiment, part of the inner passage is also enlarged and forms a chamber 510. In an embodiment, the inner passage 460 extends to the top end of the plunger, and communicates with an opening in the top 720 of the plunger. The chamber 510 may house a closure member, such as a stopper 600, is an enlarged area within the bottom end of the plunger 210. The chamber bottom can be screwed to the body of the plunger through as for example by threads, or can be threaded on and/or welded and/or pinned 904 on, or secured with screws and welded, or simply connected by welding 850. As previously mentioned, the chamber may be incorporated through an end cap 210 that is removably or permanently connected to the lower plunger body portion 500, e.g., such as threaded connection 435. See FIGS. 35-36. In any case, at least a portion of the bottom end of the plunger is preferably removable so that a closure member can be placed within the chamber. The bottom end may be attached to the body of the plunger in various ways known to one skilled in the art, including but not limited to by welding, pins, screws and the like. The bottom end 500 may have threads 435 to which parts can be attached such as a modified end cap 220.

The chamber 510 has a roof 520 at the upper end with an opening 525 in the roof, which communicates with the inner passage 460 and a floor 550 at the lower end with an opening 555. In an embodiment, there is a bore 540 that extends from the floor to the bottom of the plunger. In an embodiment, the bore 540 houses a stem 630 that is attached to the closure member. In one embodiment, the roof 520 of the chamber 510 is substantially curved and has a stopper 600 with a head 615 whose top end 610 is correspondingly curved 605, like the roof 520 of FIGS. 20 and 23. Alternatively, the roof 520 may be triangular in cross-section and the head of the stopper is correspondingly cone-shaped, like that shown in FIGS. 24-25. There are also other variations of additional shapes which the chamber roof and chamber floor could possess, such as a flat roof with straight chamber sides and a flat or curved floor, and corresponding variations of the shape of the top end and bottom end of the stopper, such as a flat top end and a circular bottom end, which could also be operable. However, for ease of manufacture, the chamber has sides 908 that are straight or substantially straight, and has a flat bottom floor 550. See FIGS. 37-38. Further, the roof is flat and has an opening 525 in it in which a portion of the stopper becomes seated. See FIGS. 37-38.

The roof 520 of the chamber 510 may also have a seating surface 530. The seating surface 530 may be or may have an area partially defined by a slanted or tapered ramp area 545 as in FIGS. 20 and 24. The seating surface 530 of the preferred embodiment is sized and designed to receive and guide a plunger stopper closure member 600 albeit rounded, half-sphere, or ball-type, upwardly to the seating surface 530 in the roof 520. The closure member may take various forms and shapes such as that shown in FIGS. 20, 23-29, 31, 33-34, 35-38, or may be in the form of a check type valve or any other type of closure member known or used by one skilled in the art. In an embodiment, the closure member is a plunger stopper 600 has a head 615 with a top end 610 and a bottom end 630. See FIGS. 37-38. A stem 650 is attached to the bottom end 630 of the head 615 of the stopper or the lower end of the closure member. The stem protrudes downward from the body of the plunger when the closure member is in the open position. See FIGS. 38. Of course the chamber could be located above the bottom end of the plunger, with a longer stem attached to the closure means.

In a further embodiment, the top end 610 of the plunger stopper 600 may also have a stem 670 that is attached thereto. This stem will be pushed up into the inner passage 460 above the chamber 510, when the bottom end 570 of the plunger hits the bottom well stop means to further ensure closure of the opening 525 into the inner passage 460. See FIGS. 24-25.

The plunger is placed within the tubulars with the closure means in the open position. Under certain conditions, the closure means such as a stopper 600 is moveable between the open position of FIG. 38, in which fluid and/or gas flow is permitted into the inlet ports, e.g., 700, 702 in the end cap 220 through the chamber 510 and into the inner passage of the body 460, through the hole 525 in the roof 520, and out through the outlet port, e.g., 710 in the top end, and the closed position of e.g., FIG. 37. The plunger body in the area near the ports must have a reduced diameter so that fluids 912 below and beside the plunger may enter the ports. See FIG. 38. FIG. 1A also shows fluids entering the chamber at the area between the plunger body and the tubulars. In FIGS. 26-29, 31, 33-37, the stopper 600 is in a closed position in which the fluid and/or gas flow through the chamber opening 545 into the passage 460 of the plunger body is blocked by the top 610 of the stopper 600.

During the decent of the plunger within the tubulars, the closure means is held in the open position by the mere weight of the closure means due to gravity, and the flow of the gas and/or fluid above the closure means through the ports that open into the chamber. The bottom of the stem must still touch the well stop to become pushed into the closed position. In the open position, a stem 650 that is attached to the bottom end of the closure means extends downwardly through the opening 555 in the hole in the floor 550 of the chamber 510 into the bore 540 in the bottom of the end cap 560, and protrudes 670 from the lower end of the plunger body 570, when the plunger is descending through the tubulars T, or at the surface once the motor valve MV has been opened such as in FIG. 1. When the stem 655 and then the bottom end of the plunger reach the bottom of the well, or some type of bottom well stop or well stop means TS, the stem 650 and the closure means is forced or pushed upwardly until the top end of the closure means is seated against the roof 520 of the chamber 510.

There may be additional outlet ports in the plunger body near the top end to increase flow. For example, the fishing part 420 may also have a plurality of outlet ports disposed around the sides of the collar 410 of the plunger body that has a reduced diameter, in addition to, or instead of the opening at the top end 720. Preferably, there is a plurality of ports, e.g., 715, 716. In an embodiment, the ports are located along the cylindrical axis of the collar. Further, in an embodiment, the ports are evenly spaced with respect to one another.

Again, there are preferably a plurality of ports that are spaced along the cylindrical axis of the end cap 220. In an embodiment, are spaced around the cap at equal distances at about 45 degrees from each other 700, 701, 702, and 703. The location of the inlet ports, e.g., 700, 702 in the chamber wall 511 of the end cap 220 are especially important. The ports 700, 702 are preferably located so that the inside openings of the ports 710, 712 into the chamber 510 are located above the top end 610 of the plunger stopper head 615 when the stopper 600 is in its downward position. FIG. 39 shows a chamber with a plurality of ports 700, 701 and 702. Furthermore, these ports are preferably located so that the inside opening of the ports 710, 712 in the chamber will be below the bottom end 630 of the stopper head 615 when the stopper is in its upward position, closing the inner passage 460. This placement of the inlet ports assures the bypassing of gases and/or liquids through the chamber passage 510 and into inner passage 460 as the plunger falls in the tubulars T.

Also in an embodiment the ports in the chamber have an oblong shape 910, such as an oval or rectangle so as to minimize the amount of surface area that would be taken out by for example, a port that is circular, that could weaken the body structure. See FIGS. 37-38.

In an embodiment the flow area through the ports in the chamber is greater than the flow through the inner passage of the plunger to create a back pressure and choking effect. This choking effect assists in keeping the stopper in the open position during the descent of the plunger.

In tests conducted in a 10,000 foot low pressure gas well, a normal pad plunger without the bypass and inner passage took about one hour to descend to the well bottom. In contrast a two-inch diameter plunger with the novel bypass with an inner passage of about one inch in diameter took only about ten to fifteen minutes to descend to the well bottom. This decreased cycle time increased the gas output of the well from about 180 mcfd (180,000 cubic feet/day) to about 330 mcfd. (330,000 cubic feet/day).

The plunger of the present invention has a number of unique elements. However, many variations of the invention can be made by those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the scope of the invention be limited only by the claims that follow. Of course, the present invention is not intended to be restricted to any particular form or arrangement, or any specific embodiment disclosed herein, or any specific use, since the present invention may be modified in various ways without departing from the spirit or scope of the claimed invention herein. Furthermore, the figures of the various embodiments is intended only for illustration and for disclosure of operative embodiments and not to show all of the various forms or modifications in which the present invention might be embodied or operated. The present invention has also been described in considerable detail in order to comply with the patent laws by providing full public disclosure of at least one of its forms. However, this detailed description is not intended to limit the broad features or principles of the present invention in any way, or to limit the scope of the patent monopoly to be granted. 

1. A plunger for use in a gas/liquid lift system in downhole production tubulars in a well producing fluids and/or gases under variable well pressures, comprising: a body slidingly engageable within the tubulars and capable of movement up and down said tubulars; said body having a top end, a bottom end, and an inner passage within said body for receiving well fluids and/or gases and enabling more rapid descent of said plunger in a well; a chamber in said body, wherein said body provides a wall at least partially surrounding said chamber, wherein said chamber is capable of receiving well fluids and/or gases; an opening between the chamber and the inner passage that allows fluid communication between the chamber and the inner passage; a closure member at least partially located inside the chamber, the closure member having a top end and a bottom end, said member being moveable between an open and a closed position; and at least one port through said wall, wherein well fluids and/or gases can flow into said chamber and into said inner passage.
 2. The plunger of claim 1, further comprising at least one opening near or at the top of said plunger, wherein said fluids and/or gas can exit out of the inner passage.
 3. The plunger of claim 1, wherein the closure member is a stopper, and wherein said stopper has a heat, a top end, and a bottom end with a stem attached thereto.
 4. The plunger of claim 1, having a plurality of ports in side walls of the plunger, the ports opening into the chamber, said ports allowing well fluids and/or gases to enter or exit the chamber.
 5. The plunger of claim 3, further comprising a roof within said chamber, and an opening in the roof, wherein a portion of the stopper rests against said roof opening in the closed position, thereby closing the opening between the chamber and the inner passage, thereby obstructing a flow of well fluids and/or gases into the inner passage.
 6. The plunger of claim 3, having a chamber with a roof and a floor, wherein said floor is parallel to the roof.
 7. The plunger of claim 3, having a stopper with a triangular head.
 8. The plunger of claim 3, having a chamber with a floor and a roof, wherein said roof is dome shaped, and said floor is nonparallel to said roof.
 9. The plunger of claim 3, having a stopper with a semicircular head.
 10. The plunger of claim 1, further comprising a fishing part attached to the top end of said plunger, the fishing part having an inner passage for the flow of fluids and/or gases.
 11. The plunger of claim 1, further comprising an opening within the floor of the chamber, wherein said bottom end of said closure member rests against the chamber floor in the open position and a stem attached to the bottom end of said closure member, said stem extending downwardly through said opening.
 12. The plunger of claim 11, wherein said stem engages a well stop when the plunger descends to the well stop, thereby pushing the stem and the closure member upward, the head of the closure member closing the opening between the chamber and the inner passage, thereby obstructing a flow of well fluids and/or gases into the inner passage, said closure member being held against the roof by a build up of pressure below the closure member.
 13. The plunger of claim 1, wherein the outlet openings of said at least one port opens into the chamber above the top end of the closure member when the closure member is in the open position and below the bottom end of the closure member when the closure member is in the closed position.
 14. The plunger of claim 4, having an inlet in the wall of the chamber that leads to said at least one port that opens into said chamber, wherein the inlet of said port is oblong in shape.
 15. The plunger of claim 1, wherein at least a portion of the plunger body has a plurality of spirals thereon.
 16. The plunger of claim 1, wherein at least a portion of the plunger body has a brush disposed thereon.
 17. The plunger of claim 1, wherein a portion of the body of the plunger body has plurality of washers thereon, said washers being movable about said body.
 18. The plunger of claim 1, having a least one external pad disposed about a portion of said plunger body.
 19. The plunger of claim 1, wherein at least a portion of the body of the plunger is coated with a compound that reduces friction between the plunger and the tubulars.
 20. A chamber for use in gas lift plungers, comprising: an cap for attachment to a gas lift plunger body, said cap having an inner passage and a chamber for receiving well liquids and/or gases, said chamber having a roof at the upper end and a floor at the lower end, with an opening in said roof that allows fluid communication with an inner passage in a plunger; and wherein a plunger stopper is at least partially located inside the chamber, the plunger stopper being moveable between an open and a closed position.
 21. The chamber of claim 20, having at least one port in said wall for the entry of well liquids and/or gases into the chamber, said at least one port having an inlet opening in the plunger body and an outlet opening in the walls of the chamber, with a passage between the inlet and the outlet, wherein the outlet openings of said port is positioned in the chamber above the top end of the stopper when the stopper is in the open position and below the bottom end of the stopper when the stopper is in the closed position.
 22. The chamber of claim 20, further comprising an opening in the floor that communicates with a bore below the floor, said bore extending downward and having an opening at the bottom of said cap.
 23. The chamber of claim 20, the stopper has a head, the head having an upper end and a lower end, the upper end of the head resting against the roof in the closed position, the lower end having a stem attached thereto, and resting against the chamber floor in the open position and the stem extending downwardly through said opening in the floor and into said bore and extending outwardly from said bottom end opening, whereby the stem engages a well stop when the plunger descends down the well tubulars thereby pushing the stopper stem and the head upward, at least a portion of the head being seated against the roof to close the opening between the chamber and the inner passage, thereby obstructing a flow of well liquids and/or gases into the inner passage, said stopper being held against the roof by a build up of pressure below the stopper.
 24. The chamber of claim 20, wherein said cap is securably or removably attached to said plunger body.
 25. The chamber of claim 20, used in a plunger wherein at least a portion of the plunger body has a plurality of spirals thereon.
 26. The chamber of claim 20, used in a plunger wherein at least a portion of the plunger body has a brush disposed thereon.
 27. The chamber of claim 20, used in a plunger wherein a portion of the body of the plunger body has plurality of washers thereon, said washers being movable about said body.
 28. The chamber of claim 20, used in a plunger having a least one external pad disposed about a portion of said plunger body.
 29. The chamber of claim 20, used in a plunger body wherein at least a portion of the plunger body is coated with a compound that reduces friction.
 30. The chamber of claim 20, wherein said chamber has a roof that is parallel to said floor.
 31. The plunger of claim 20, wherein said chamber has a roof that is nonparallel to said floor.
 32. A method of lifting well liquids and/or gases from a subterranean reservoir to a well surface in tubulars in a well by increasing pressure in the well tubulars, comprising: providing a plunger with a body that is capable of movement up and down said tubulars, said body having a top end, a bottom end, and an inner passage within said body for receiving well fluids and/or gases and enabling more rapid descent in a well; making a chamber within said plunger body for receiving well fluids and/or gases, with an opening that communicates with the inner passage and wherein well liquids and/or gases can flow into said chamber and into said inner passage, wherein said body provides at least one side wall at least partially surrounding said chamber; placing a stopper at least partially inside the chamber, the stopper being moveable between an open and a closed position; positioning the closure means in the open position; putting said plunger in a well having tubulars that produces fluids and/or gases; and allowing said plunger to descend or gravitate to the well bottom or well stop.
 33. The method of claim 32, further comprising step of attaching a stem to the stopper and positioning the stopper so that the stem extends outside the bottom of said plunger body, wherein said stem contacts said well bottom or well stop when said plunger gravitates down said tubulars, thereby pushing said stopper upwardly to close said opening to said inner passage.
 34. The method of claim 33, further comprising steps of: allowing pressure to build up in the well to a predetermined or desired level and enabling fluids from a reservoir to accumulate in the well; and opening a valve connected to the tubulars that decreases the pressure inside the tubulars thereby elevating the plunger and the accumulated well fluids and/or gases to the surface.
 35. The method of claim 32, further comprising the step of attaching a fishing part to the top end, said fishing part having an inner passage for the flow of fluids and/or gases.
 36. The method of claim 32, further comprising the step of placing a plurality of ports disposed in side walls of the fishing part, the ports having an inlet opening in the walls of the inner passage and an outlet opening in the fishing part, said ports allowing well fluids and/or gases to exit the inner passage when the stopper is in the open position.
 37. The method of claim 32, further comprising the step of providing a plurality of ports in the chamber wall, said ports allowing well fluids and/or gases to enter or exit the chamber.
 38. The method of claim 32, wherein the flow of said liquids and/or gases into said chamber is greater than the flow of said liquids and/or gases into the inner passage, thereby creating a choking effect.
 39. The method of claim 38, wherein the choking effect assists in keep the stopper in the open position.
 40. The method of claim 32, further comprising steps of: placing the plunger in the tubulars without shutting in the well; and allowing the plunger to ascend to the well surface when sufficient pressure has built up in the well. 